1. Field of the Invention
The present invention relates to imaging systems. More particularly, it relates to imaging devices having a fixed focal length.
2. Related Art
Many imaging systems have an imager that receives energy and converts the received energy into a form of data known as pixels. This pixel data can then be stored by these imaging systems for subsequent retrieval and processing and/or transmitted to a remote receiving station for storage and processing. Pixel data can be processed using known signal processing techniques. Improving the signal quality and/or reducing the data output rates of these imaging systems is highly desirable.
Imaging systems having a fixed focal length imager are designed to image objects or areas with a minimum image resolution while operating at a maximum design distance from the objects or areas to be imaged. If these imaging systems are used to image objects at a distance in excess of their maximum design distance, they will not be able to achieve their designed minimum image resolution. These imaging systems are often used, however, to image objects or areas that are nearer then their maximum design distance. For example, certain airborne imaging systems are designed to image ground objects with a minimum image resolution while being carried aboard an aircraft flying at a specified maximum altitude. But, since the operational envelope of an aircraft covers a range of flying altitudes, there are often times when these airborne imaging systems are used while being carried aboard an aircraft flying at an altitude less than the specified maximum design altitude for the imaging system. When this occurs, these imaging systems will have an achievable image resolution in excess of their designed minimum image resolution and a less than optimal signal-to-noise ratio. Moreover, when this occurs, there is an excess of pixel data that must be stored by these imaging systems for subsequent retrieval and processing and/or transmitted to a remote receiving station for storage and processing. This is a less than desirable situation when high speed data transmission or processing is required.
What is needed is a means for improving the signal quality and/or reducing the data output rates of imaging systems having an achievable image resolution in excess of their designed minimum image resolution.